Certain cyclopropane carboxylic acid esters of 2,3-dihyrobenzofuran-3-ols

ABSTRACT

Cyclopropanecarboxylic acid esters of 3-coumaranol and substituted 3-coumaranols possessing useful insecticidal properties.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.2,443, filed Jan. 12, 1970, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to novel cyclopropanecarboxylic acid esters of3-coumaranol, and derivatives thereof, as well as insecticidalcompositions containing said esters as an essential active ingredient.

Current trends in the chemical control of insects call for inherentlysafer materials which degrade very rapidly to non-toxic substances oncetheir purpose is accomplished. The safety of the widely used chlorinatedhydrocarbons, notably DDT, is currently under question largely becauseof their poor biodegradability and concomitant persistence. Accordingly,there is a great demand for alternative broad spectrum insecticideswhich are suitable for the high volume usage entailed in agriculturalapplications. At the same time it is desirable for new insecticides toexhibit a low order of toxicity to warm-blooded animals. Of the severalinsecticidal classes which demonstrate low mammalian toxicity and goodbiodegradability, it has long been recognized that pyrethrum, anaturally-occurring insecticidal mixture, possesses these desirableproperties. In addition to the safety advantages, this natural mixturecauses rapid knock-down and kill of a broad spectrum of insects;however, it is unstable to light, air, and heat, and is very expensive.The most active component of pyrethrum is pyrethrin I and a number ofanalogous compounds have been proposed for insecticidal use. Allethrin,a typical synthetic pyrethrin-like insecticide, while more stable tolight and heat than pyrethrum, is nevertheless expensive, a defect whichis compounded by the fact that this substance is not appreciablysynergized by the low cost synergizing agents such as piperonyl butoxidewhich are typically used in insecticidal compositions. Because ofinstability, high cost and limited supply, the use of pyrethrum andpyrethrin-like insecticides in agricultural applications has beenprecluded or seriously limited.

At the same time, it is well known that certain insects, in time, becomeimmune to the insecticidal properties of various chemical agents. To beefficient, an insecticide should be able to resist detoxification by theinsect. While biological mechanisms whereby insects are capable ofdetoxifying the various types of insecticidal compounds are not fullyunderstood, it is possible that, as with other biological systems,insects may in time develop new biochemical processes capable ofdetoxifying any particular insecticidal compound. In any event, it isdesirable to have included in the insecticidal armamentarium compoundswhich can be utilized once a given class of insects is found no longerto respond to conventional insecticidal compounds.

Many prior art insecticidal esters differ from one another and from thenatural pyrethrin I esters by virtue of synthetic modifications in thealcohol moiety of the ester. Other synthetic insecticides arepyrethrin-like esters modified in the acid portion of the estermolecule. For example, the applications of Fanta, entitled "INSECTICIDALESTERS OF 3-(2,2-TETRAMETHYLENEETHENYL)-2,2-DIMETHYLCYCLOPROPANECARBOXYLIC ACID," Ser. No. 23,513,filed Mar. 17, 1970 (now U.S. Pat. No. 3,679,667 issued July 25, 1972);"NOVEL ESTERS OF CHRYSANTHEMIC ACID", Ser. No. 2,443, filed Jan. 12,1970 now abandoned; the copending application of Crawford, entitled"INSECTICIDAL ESTERS OF 1-ACENAPHTHENOL", Ser. No. 198,434, filed Nov.12, 1971 now U.S. Pat. No. 3,840,584 and U.S. Pat. 3,465,007, Sept. 2,1969, to M. Elliott, all relate to various synthetic insecticidal estersof the pyrethrum type. It has now been discovered that 3-coumaranol, andthe various derivatives thereof, can be used in conjunction withcyclopropanecarboxylic acids to provide insecticidal esters of thepyrethrum type.

It is therefore an object of this invention to provide novelinsecticidal 3-coumaranol esters of cyclopropanecarboxylic acids whichare biodegradable, effect rapid knock-down and kill of a broad-spectrumof insects, possess low mammalian toxicity and are less susceptible todetoxification by insects than is pyrethrum. This and other objects areobtained by the present invention as will become apparent from thefollowing disclosure.

SUMMARY OF THE INVENTION

The novel compounds of the present invention include certaincyclopropanecarboxylic acid esters of 3-coumaranol and substitutedderivatives of 3-coumaranol. (The "3-coumaranol" compounds may bealternatively named as derivatives of 2,3-dihydro-3-benzofurylcompounds; the "chyrsanthemic acid" esters herein can also be named asderivatives of 2,2-dimethyl-3-(2-methylpropenyl) cyclopropanecarboxylicacid.)

This invention also encompasses insecticidal compositions comprising asan essential ingredient an insecticidal amount of certaincyclopropanecarboxylic acid esters of 3-coumaranol or a substituted3-coumaranol.

As a method aspect, the present invention encompasses a method ofcombatting insects comprising applying a insectidal amount of acyclopropanecarboxylic acid ester of 3-coumaranol or substituted3-coumaranol to an insect or insect habitat.

DETAILED DESCRIPTION OF THE INVENTION

The cyclopropanecarboxylic acid esters of 3-coumaranol, and derivativesof 3-coumaranol are of the formula ##STR1## wherein R is a cyclopropanemoiety selected from the group consisting of ##SPC1##

wherein n is an integer of from 4 to 6, preferably 4, and wherein R¹ isa 3-coumaranyl moiety of the formula ##SPC2##

wherein R² is selected from the group consisting of hydrogen, halogen,nitro, thiomethyl, alkyl (e.g., ethyl, methyl, propyl, butyl, neopentyl,isopropyl,), alkoxy (e.g., methoxyl, ethoxyl), sulfonylmethyl, phenyl,benzyl, and the like. The esterification is at the 3-position on thecoumaranol ring system.

The insecticidal compounds of this invention are prepared by esterifying3-coumaranol and substituted derivatives thereof, withcyclopropanecarboxylic acids or acid halides in the manner hereinafterdetailed. First, the 3-coumaranol compound is prepared by reactingsalicylaldehyde or a 5-substituted salicylaldehyde withdimethyloxosulfonium methylide to secure the corresponding 3-coumaranolin accordance with the method described by B. Holt and P. A. Lowe,Tetrahedron Letters, No. 7, 683 (1966) as detailed by E. J. Corey and M.Chaykovski, J. Amer. Chem. Soc., 87, 1353 (1965). The reaction proceedsas follows: ##SPC3##

wherein R² is as above. Following this, the 3-coumaranol compound isesterified, e.g., by means of a cyclopropanecarboxylic acid halide, asfollows: ##SPC4##

wherein R is as disclosed above.

According to the above outline, the esters of this invention areprepared by a step-wise process comprising: (1) preparing the3-coumaranol compound according to the procedures described in theforegoing references; (2) esterifying the alcohol with a stoichiometricamount of a cyclopropanecarboxylic acid chloride which is also preparedby standard procedures (below).

Alternatively, the esterification step of the present invention can beeffected in other ways. The 3-coumaranol compound can be heated with theappropriate cyclopropanecarboxylic acid in the presence of a strong acid(e.g., H₂ SO₄, HClO₄, etc.) in an organic solvent capable ofazeotropically boiling with water, thereby removing the water formed inthe esterification. The 3-coumaranol compound can also be heated with alower alkyl ester of a cyclopropanecarboxylic acid in the presence of abasic catalyst such as sodium hydroxide, potassium hydroxide, sodiumalcoholate, or potassium alcoholate, and the like, while continuouslyremoving the lower alcohol formed through trans-esterification of thereaction system. In such cases, the methyl, ethyl, n-propyl andiso-propyl esters of the cyclopropanecarboxylic acids are suitable. Inthe most preferable esterification, the 3-coumaranol compound is allowedto react with a cyclopropanecarboxylic acid halide, preferably attemperatures from about 20°C to about 100°C, in an inert solvent,preferably in the presence of an agent such as pyridine, triethylamineor other suitable amine, such that the esterification proceeds with theformation of a hydrohalic acid salt within a short period of time. Forthis purpose, the cyclopropanecarboxylic acid chloride is the mostpreferred, although the acid bromide and the acid iodide can beemployed.

The cyclopropane carboxylic acids used to prepare the insecticidalesters of the instant invention can be prepared by standard proceduresdisclosed in the art. U.S. Pat. No. 3,679,667, filed July 25, 1972,above, describes the preparation of 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylic acid; chrysanthemoylchloride can be prepared in the manner of Crombie, et al., J. Chem. Soc.3552 (1950); 2,2,3,3-tetramethylcyclopropanecarboxylic acid can beprepared in the manner of Matsui and Kitahara, Agr. Biol. Chem. (Tokyo)31, 1143 (1967) and converted to the acid chloride using thionylchloride.

Exemplary 3-coumaranol compounds useful herein include the 5-halo-(i.e.,fluoro, chloro, bromo and iodo) 3-coumaranols, 5-nitro-3-coumaranol,3-coumaranol, 5-methoxy-3-coumaranol, 5-butoxy-3-coumaranol,5-decyl-3-coumaranol, 5-sulfonylmethyl-3-coumaranol,5-thiomethyl-3-coumaranol and the like. 3-Coumaranol compounds preferredfor use in the preparation of the compounds of this invention by virtueof their low cost, ease of preparation and the high insecticidalactivity of the cyclopropanecarboxylic esters which they form include:3-coumaranol, 5-methoxy-3-coumaranol, 5-chloro-3-coumaranol,5-methyl-3-coumaranol and 5-nitro-3-coumaranol.

The compounds of this invention can exist in several isomeric andoptically isomeric forms, e.g., cis-configuration, trans-configuration,dextro- and levorotatory forms of each, etc., and mixtures and racematesthereof. It is intended that the claims herein be construed to encompassall such forms and mixtures thereof. Preferred insecticidal estersherein are 3-coumaranyl chrysanthemate, 5-chloro-3-coumaranylchrysanthemate, 5-nitro-3-coumaranyl chrysanthemate,5-methoxy-3-coumaranyl chrysanthemate, 3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate, 5-chloro-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate, 5-nitro-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate, 5-methoxy-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate, 3-coumaranyl3-(2,2-tetramethylene ethenyl)-2,2-dimethylcyclopropanecarboxylate,5-chloro-3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylate, 5-nitro-3-coumaranyl3-(2,2-tetramethylene ethenyl)-2,2-dimethylcyclopropanecarboxylate,5-methoxy-3-coumaranyl 3-(2,2,-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylate, 5-phenyl-3-coumaranylchrysanthemate, 5-benzyl-3-coumaranyl chrysanthemate,5-phenyl-3-coumaranyl 2,2,3,3,-tetramethylcyclopropanecarboxylate,5-benzyl-3-coumaranyl 2,2,3,3,-tetramethylcyclopropanecarboxylate,5-phenyl-3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylate and 5-benzyl-3 -coumaranyl3-(2,2-tetramethylene ethenyl)-2,2-dimethylcyclopropanecarboxylate.

The preparation of the coumaranyl cyclopropanecarboxylic acid esters ofthe present invention is described in more detail in the followingexamples. The inert organic solvents used in the procedure are thosewhich do not react with the 3-coumaranyl compounds or with thecyclopropanecarboxylic acids or acid halides. Such solvents arepreferably aprotic solvents such as hexane, benzene, acetone, ether,glyme, and the like. The examples are not intended to be limiting butonly to demonstrate the preparation of a variety of compounds of thisinvention.

EXAMPLE I

Step 1. According to the precedure of Corey and Chakovski, above, anitrogen blanketed mixture of 2.52 g. (0.064 mol.) of sodium hydride (asa 61% mineral oil dispersion) and 14.1 g (0.064 mol.) oftrimethyloxosulfonium iodide was stirred and treated dropwise over 15min. with 70 ml. of dry dimethyl sulfoxide. The reaction mixture wasthen cooled to 10°C and a solution of 7.32 g. (0.06 mol.) ofsalicylaldehyde in 30 ml. of dry dimethyl sulfoxide was added in oneportion with stirring. After 5 min. the cooling bath was removed andstirring was continued at room temperature for 2 hours and at 50°C for 1hour. The cooled reaction mixture was poured into ice water and theaqueous mixture extracted with ether. The combined ether extracts werewashed twice with water, once with saturated salt solution, and driedover magnesium sulfate. Evaporation of the solvent at reduced pressureyielded 7.2 g. (88%) of 3-coumaranol.

Further purification by passing through a Florisil column afforded 5.87g. of product: ir (neat) 2.98, 6.20, 6.23, 6.75, 8.1, 10.4, 13.2μ; nmr(CCl₄) τ 3.0 (multiplet, 4 hydrogens, aromatic), 5.0 (multiplet, 1-hydrogen, -CHOH), 5.81 (multiplet, 2 hydrogens, --CH₂ --), 6.62(singlet, 1 hydrogen, OH).

Step 2. A mixture of 11 g. (0.059 mol.) of (±)-chrysanthemoyl chloride(mixture of cis- and trans-isomers) and 9.5 g. (0.12 mol.) of drypyridine in 125 ml. of dry benzene was cooled to 0°C. A solution of 8.05g. (0.059 mol.) of the 3-coumaranol prepared in the first step in 25 ml.of dry benzene was added with stirring over several minutes. The coolingbath was removed and the reaction mixture was stirred at roomtemperature for 24 hours. The reaction was added to saturated saltsolution and the layers were separated. The aqueous layer was furtherextracted with ether and the combined organic layers were washed twicewith 3% aqueous hydrochloric acid and several times with saturated saltsolution prior to drying with magnesium sulfate. Evaporation of thesolvent at reduced pressure gave 20 g. of crude ester product. This waspurified by passing through a Florisil column to yield 14 g. (83%) of(±) cis,trans-3-coumaranyl chrysanthemate; ir(neat) 3.42, 5.79, 6.20,6.23, 8.61, 13.2μ; nmr(CCl₄) τ 2.64-3.4 (multiplet, 4 -hydrogens,aromatic) 3.92 (multiplet, 1 hydrogen, ##STR2## 4.75, 5.26 [2 doublets,1 hydrogen, J = 8 Hz, cis and trans (CH₃)₂ C=CH--] 5.62 (multiplet, 2hydrogens, --CH₂ O--), 8.36 [singlet, 6 hydrogens, (CH₃)₂ C=], 8.78,8.90 [2 singlets, ##STR3## n_(D) ²⁵.sup.° 1.5271.

In the above procedure, the chrysanthemoyl chloride is replaced by anequivalent amount of 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylic acid chloride and2,2,3,3-tetramethylcyclopropanecarboxylic acid chloride, respectively,and the compounds 3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylate and 3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate are secured.

EXAMPLE II

In the same manner as described in Example I, Step 1, 1.26 g. (0.032mol.) of sodium hydride (as a 61% mineral oil dispersion) and 7. g.(0.032 mol.) of trimethyloxosulfonium iodide in 35 ml. of dry dimethylsulfoxide was treated with a solution of 4.68 g. (0.030 mol.) of5-chlorosalicylaldehyde in 15 ml. of dimethyl sulfoxide. Chromatographicpurification gave 2.5 g. (49%) of 5-chloro-3-coumaranol: m.p. 85°-86°C;ir(CCl₄) 2.78, 2.94, 3.38, 6.2, 6.78, 10.3μ; nmr (CDCl₃) τ 2.5-3.4(multiplet, 3 hydrogens, aromatic), 4.92 (multiplet, 1 hydrogen, -CHOH),5.76 (multiplet, 2 hydrogens, -CH₂ -), 6.80 (singlet, 1 hydrogen, OH).

As described in Example I, Step 2, a solution of 2 g. (0.012 mol.) of5-chloro-3-coumaranol in 8 ml. of dry benzene was allowed to react witha solution of 2.2 g. (0.012 mol.) of chrysanthemoyl chloride and 1.9 g.(0.024 mol.) of dry pyridine in 10 ml. of dry benzene to yield 2.33 g.(61%) of (±) cis,trans-5-chloro-3-coumaranyl chrysanthemate, a viscousliquid: ir(film) 3.42, 5.78, 6.2, 6.78, 8.62μ; nmr (CCl₄) τ 2.64-3.4(multiplet, 3 hydrogens, aromatic), 3.9 (multiplet, 1 hydrogen, ##STR4##5.56 (multiplet, 2 hydrogens, --CH₂ --), 8.36 [singlet, 6 hydrogens,(CH₃)₂ C=], 8.74, 8.92 [2 singlets, ##STR5##

In the above procedure, the chrysanthemoyl chloride is replaced by anequivalent amount of 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylic acid chloride and2,2,3,3-tetramethylcyclopropanecarboxylic acid chloride, respectively,and the compounds 5-chloro-3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylate and 5-chloro-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate are secured.

EXAMPLE III

In the same manner as described in Example I, Step 1, 1.26 g. (0.032mol.) of sodium hydride (as a 61% mineral oil dispersion) and 7 g.(0.032 mol.) of trimethyloxosulfonium iodide in 35 ml. of dry dimethylsulfoxide was treated with a solution of 4.56 g. (0.030 mol.) of5-methoxysalicylaldehyde in 15 ml. of dimethyl sulfoxide.Chromatographic purification gave 1.6 g. (32%) of5-methoxy-3-coumaranol: ir(neat) 2.98, 3.4, 6.73, 8.8, 9.74, 10.4μ; nmr(CCl₄) τ 2.3-3.5 (multiplet, aromatic) 4.92 (multiplet, --CHOH), 5.72(multiplet, --CH₂ --), 6.4 (singlet, --OCH₃), 7.2 (singlet, --OH).

As described in Example I, Step 2, a solution of 2 g. (0.012 mol.) of5-methoxy-3-coumaranol in 8 ml. of dry benzene was allowed to react witha solution of 2.2 g (0.012 mol.) of chrysanthemoyl chloride and 1.9 g.(0.024 mol.) of dry pyridine in 10 ml. of dry benzene to yield 2.3 g.(61%) of (±) cis, trans- 5-methoxy-3-coumaranyl chrysanthemate as aviscous liquid: ir(neat) 3.39, 5.79, 6.18, 6.25, 6.78μ; nmr(CCl₄) τ2.5-3.6 (multiplet, aromatic), 3.95 (multiplet, ##STR6## 6.04(multiplet, -CH₂ -), 6.4 (singlet, -OCH₃), 8.4 [singlet, (CH₃)₂ C=],8.8, 8.95 [2 singlets, ##STR7##

In the above procedure, the chrysanthemoyl chloride is replaced by anequivalent amount of 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylic acid chloride and2,2,3,3-tetramethylcyclopropanecarboxylic acid chloride, respectively,and the compounds 5-methoxy-3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylate and 5-methoxy-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate are secured.

In the above procedure, the 5-methoxysalicylaldehyde is replaced by anequivalent amount of 5-nitrosalicylaldehyde and 5-nitro-3-coumaranyl issecured. Esterification of the 5-nitro-3-coumaranyl with the respectivecyclopropanecarboxylic acid chlorides in the foregoing manner affords5-nitro-3-coumaranyl chrysanthemate, 5-nitro-3-coumaranyl3-(2,2-tetramethylene ethenyl)-2,2-dimethylcyclopropane carboxylate and5-nitro-3-coumaranyl 2,2,3,3-tetramethylcyclopropanecarboxylate,respectively.

Additional compounds encompassed by the present invention can beprepared as in Example I by replacing the salicylaldehyde in Step 1 with5-methylsalicylaldehyde, 5-ethylsalicylaldehyde, 5-phenylsalicylaldehydeand 5-benzylsalicylaldehyde, respectively. Esterification of theresulting 5-substituted-3-coumaranols with the foregoingcyclopropanecarboxylic acid halides yields 5-methyl-3-coumaranylchrysanthemate; 5-ethyl-3-coumaranyl chrysanthemate;5-methyl-3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropane carboxylate; 5-ethyl-3-coumaranyl3-(2,2-tetramethylene ethenyl)-2,2-dimethylcyclopropanecarboxylate;5-methyl-3-coumaranyl 2,2,3,3-tetramethylcyclopropanecarboxylate;5-ethyl-3-coumaranyl 2,2,3,3-tetramethylcyclopropanecarboxylate, and the5-phenyl-3-coumaranyl- and 5-benzyl-3-coumaranylchrysanthemates,2,2,3,3-tetramethylcyclopropanecarboxylates and 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylates, respectively.

The outstanding insecticidal properties of the compounds of thisinvention can be seen from the following examples:

EXAMPLE IV

3-Coumaranyl chrysanthemate, 5-chloro-3-coumaranyl chrysanthemate,5-methoxy-3-coumaranyl chrysanthemate, and natural pyrethrum,respectively, were dissolved in acetone and dispersed in distilled waterwith Triton X-100 emulsifier. The samples were applied for a 10 secondperiod to houseflies retained in a 2 inch × 5 inch diameter screenedcage. The spray is applied from the Water's vertical spray toweroperating at 10 p.s.i. and discharging about 30 ml. of material perminute through an atomizer. The spray descends through an 8 inchstainless steel cylinder to test insects below the atomizer. The insectswere retained in the sprayed cages for mortality observations. Theresults are set forth in Table 1 below.

                  TABLE 1                                                         ______________________________________                                        Housefly Mortality Tests                                                      Chrysanthemic               % Mortality                                       Acid Ester % W/V            (24 hr.)                                          ______________________________________                                        3-coumaranol                                                                             0.0025           6                                                 (Example I)                                                                              0.0025 + 0.025 PB*                                                                             93                                                           0.00125          5                                                            0.00125 + 0.0125 PB*                                                                           28                                                5-chloro-3-                                                                              0.005            5                                                 coumaranol                                                                    (Example II)                                                                             0.005 + 0.05 PB* 99                                                           0.0025 + 0.025 PB*                                                                             56                                                5-methoxy-3-                                                                             0.01             0                                                 coumaranol                                                                    (Example III)                                                                            0.01 + 0.1 PB*   100                                                          0.005 + 0.05 PB* 57                                                Pyrethrum  0.0025           20                                                           0.0025 + 0.025 PB*                                                                             96                                                           0.00125          1                                                            0.00125 + 0.0125 PB*                                                                           46                                                ______________________________________                                         *Piperonyl butoxide, an insecticidal synergist, has essentially no            insecticidal activity at the concentrations reported above.              

In the above test, the respective chrysanthemates are replaced by anequivalent amount of 3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2-dimethylcyclopropanecarboxylate, 3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate, 5-chloro-3-coumaranyl3-(2,2-tetramethylene ethenyl)-2,2-dimethylcyclopropanecarboxylate,5-chloro-3-coumaranyl 2,2,3,3-tetramethylcyclopropanecarboxylate,5-methoxy-3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylate, 5-methoxy-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate, 5-nitro-3-coumaranylchrysanthemate, 5-nitro-3-coumaranyl 3-(2,2-tetramethyleneethenyl)-2-dimethylcyclopropanecarboxylate, and 5-nitro-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate, respectively, and equivalentresults are secured.

EXAMPLE V

3-Coumaranyl chrysanthemate and natural pyrethrum, respectively, wereformulated in deodorized kerosene to give a deposit rate of 100milligrams per square foot of area for residual evaluation againsthouseflies and 200 and 400 milligrams per square foot of area forresidual evaluation against German cockroaches. The formulations wereuniformly applied at the rate of 8 milliliters/sq.ft. on unpaintedplywood and 3.5 milliliters/sq.ft. on vinyl asbestos with a camel hairbrush. Adult insects were exposed to each treated panel for one hour(houseflies) or two hours (cockroaches), transferred to clean cages, andheld for mortality counts. The same treated panels were used forre-exposures after the aging period indicated.

The results were as follows:

                                      TABLE 2                                     __________________________________________________________________________    Residual Activity Against Houseflies                                                  Surface Age of       % Mortality                                      Ester   Type    Residue (Days)                                                                             (24 hr.)                                         __________________________________________________________________________    3-coumaranol                                                                          Plywood 1            100 ( 9)*                                        (Example I)                                                                                   3            98  (21)                                                         7            83  ( 0)                                                 Vinyl   1            100 (68)                                                         3            100 ( 0)                                                         7            59  ( 0)                                         __________________________________________________________________________    Residual Activity Against Cockroaches                                                                      %                                                        Surface                                                                            Milligrams                                                                           Age of Residue                                                                         Mortality                                        Ester   Type per sq. ft.                                                                          (Days)   (48 hrs.)                                        __________________________________________________________________________    3-coumaranol                                                                          Plywood                                                                            400    1        83  (100)*                                       (Example I)                                                                                       3        83  (100)                                                            7        90  (100)                                                            14       73  (85)                                                      200    1        85  (100)                                                            3        83  (100)                                                            7        93  ( 95)                                                            14       85  ( 65)                                                Vinyl                                                                              400    1        100 (100)                                                            3        100 (100)                                                            7        100 (100)                                                            14       83  (100)                                                     200    1        100 (100)                                                            3        95  (100)                                                            7        70  (100)                                                            14       20  ( 65)                                        __________________________________________________________________________     *The values set forth in parentheses are those secured for pyrethrum whic     serves as a positive control.                                            

In the above procedure, the 3-coumaranyl chrysanthemate is replaced byan equivalent amount of the 5-ethyl-3-coumaranyl-,5-methoxy-3-coumaranyl-, 5-bromo-3-coumaranyl-,5-thiomethyl-3-coumaranyl-, 5-nitro-3-coumaranyl-,5-sulfonylmethyl-3-coumaranyl-, 5-propoxy-3-coumaranyl-,5-butoxy-3-coumaranyl-, 5-benzyl-3-coumaranyl-, and5-phenyl-3-coumaranyl- esters of chrysanthemic acid,3-(2,2-tetramethylene ethenyl)-2,2-dimethylcyclopropanecarboxylic acid,and 2,2,3,3-tetramethylcyclopropanecarboxylic acid, respectively, andequivalent results are secured.

EXAMPLE VI

3-Coumaranyl chrysanthemate has also been shown to be effective against11 other insects as follows. All test species except the webbing clothesmoth larvae were sprayed in the Water's vertical spray tower asdescribed in Example IV. For the fabric tests, a two inch square area ofwool fabric was dipped in the test formulations. The results securedwith various insects are set forth below.

                                      TABLE 3                                     __________________________________________________________________________    Insect Mortality Tests                                                                    Test compound                                                                          Pyrethrum +                                                                           %                                                            + synergist*                                                                           synergist*                                                                            Mortality                                        Insect      (% W/V)  (% W/V) (days)                                           __________________________________________________________________________    Southern Armyworm                                                                         0.05 + 0.2        70 (2)                                                               0.05 + 0.2                                                                            100 (2)                                          Mexican Bean Beetle                                                                       0.005 + 0.02      80 (2)                                                               0.005 + 0.02                                                                           30 (2)                                          Pea Aphid   0.005 + 0.02      65 (2)                                                               0.005 + 0.02                                                                          100 (2)                                          Mite        0.05 + 0.2        69 (5)                                                               0.05 + 0.2                                                                            100 (5)                                          German Cockroach                                                                          0.05 + 0.2        30 (2)                                                               0.05 + 0.2                                                                             85 (2)                                          Adult mosquito                                                                            0.05 + 0.2       100 (1)                                                               0.05 + 0.2                                                                            100 (1)                                          Adult stable flies                                                                        0.05 + 0.2       100 (1)                                                               0.05 + 0.2                                                                            100 (1)                                          Black carpet                                                                              0.05 + 0.2        40 (7)                                          beetle larvae        0.05 + 0.2                                                                             40 (7)                                          Webbing clothes                                                                           0.05 + 0.2       100 (7)                                          moth larvae          0.05 + 0.2                                                                            100 (7)                                          Adult rice weevils                                                                        0.05 + 0.2       100 (3)                                                               0.05 + 0.2                                                                            100 (3)                                          Adult saw toothed                                                                         0.05 + 0.2       100 (3)                                          grain beetles        0.05 + 0.2                                                                            100 (3)                                          __________________________________________________________________________     *Synergist - Piperonyl butoxide                                          

In the above procedure, the 3-coumaranyl chrysanthemate is replaced byan equivalent amount of the 5-ethyl-3-coumaranyl-,5-methoxy-3-coumaranyl-, 5-bromo-3-coumaranyl-,5-thiomethyl-3-coumaranyl-, 5-nitro-3-coumaranyl-,5-sulfonylmethyl-3-coumaranyl-, 5-propoxy-3-coumaranyl-, and5-butoxy-3-coumaranyl- esters of 3-(2,2-tetramethyleneethenyl)-2,2-dimethylcyclopropanecarboxylic acid and2,2,3,3-tetramethylcyclopropanecarboxylic acid, and the5-ethyl-3-coumaranyl-, 5-methoxy-3-coumaranyl-, 5-bromo-3-coumaranyl-,5-thiomethyl-3-coumaranyl-, 5-nitro-3-coumaranyl-,5-sulfonylmethyl-3-coumaranyl-, 5-propoxy-3-coumaranyl-, and5-butoxy-3-coumaranyl- esters of chrysanthemic acid, respectively, andequivalent results are secured.

As can be seen from the foregoing examples, representative compounds ofthis invention possess excellent insecticidal properties, comparingfavorably with pyrethrum in most aspects and surpassing it in residualeffect. Additionally, the esters herein are less toxic to mammals thanpyrethrum as can be seen by the LD₅₀ values of one of the typical estersherein.

    ______________________________________                                        Compound               LD.sub.50 (rat)                                        ______________________________________                                        3-coumaranyl chrysanthemate                                                                          >7.57 g./kg.                                           Pyrethrum               2.3 g./kg.                                            ______________________________________                                    

The other esters herein are also less toxic than their correspondingpyrethrum analogs.

Insecticidal compositions containing the esters of the present inventioncan be formulated and utilized as oil solutions emulsifiableconcentrates, wettable powders, dusts, aerosols, or impregnated intowood, fabrics, etc., and provide a long lasting residual effect. Suchcompositions can include the generally employed carriers or diluents andauxiliary agents which are well-known to those skilled in the art. Forexample, suitable dusts can be prepared by admixing the compounds of theinvention with dry free-flowing powders such as clay, bentonite,fuller's earth, diatomaceous earth, pyrophyllite, attapulgite, calciumcarbonate, chalk or the like. The active compounds of the inventionnormally comprise up to about 10% by weight of such dust formulations.An amount of up to about 3% is preferred and is suitable for mostapplications.

Likewise, suspensions or dispersions of the compounds in a non-solvent,such as water, can be suitably employed for the treatment of foliage.Also suitably employed are solutions of the insecticides of thisinvention in oil which is emulsified in water. Examples of oil solventsinclude hydrocarbons such as benzene and toluene, halogenatedhydrocarbons such as chlorobenzene, chloroform, fluorotrichloromethaneand dichlorodifluoromethane, and commercial mixtures of hydrocarbonssuch as the common Stoddard solvent, petroleum ethers, and the like.

Aerosols can be prepared by dissolving the compounds of the invention ina highly volatile liquid carrier such as trifluorochloromethane,nitromethane, dichlorodifluoroethane and the like, or by dissolving suchcompounds in a less volatile solvent, such as benzene or kerosene, andadmixing the resulting solution with a highly volatile liquid aerosolcarrier such as the polyfluorohydrocarbons commonly used as aerosolpropellants.

The insecticidal esters of this invention are useful for destroying avariety of insects. Accordingly, a method aspect of the presentinvention comprises combating insects by applying to said insects, or toan insect habitat, an insecticidal amount of one or more of the novelcompounds disclosed herein.

Preferably the esters of this invention are employed in combination witha synergistic agent, for example, piperonyl butoxide, piperonylsulfoxide, β-butoxy-2'-thiocyanodiethyl ether and the like.

What is claimed is:
 1. A compound of the formula ##EQU1## wherein R is acyclopropane moiety selected from the group consisting of ##SPC5##andwherein R¹ is a 3-coumaranyl moiety of the formula ##SPC6## wherein R²is selected from the group consisting of hydrogen, halogen, nitro,thiomethyl, alkyl, alkoxyl, sulfonylmethyl, phenyl and benzyl.
 2. Acompound according to claim 1 wherein R is a cyclopropane moiety of theformula: ##SPC7##
 3. A compound according to claim 2 which is3-coumaranyl chrysanthemate.
 4. A compound according to claim 2 which is5-chloro-3-coumaranyl chrysanthemate.
 5. A compound according to claim 2which is 5-nitro-3-coumaranyl chrysanthemate.
 6. A compound according toclaim 2 which is 5-methoxy-3-coumaranyl chrysanthemate.
 7. A compoundaccording to claim 2 which is 5-methyl-3-coumaranyl chrysanthemate.
 8. Acompound according to claim 2 which is 5-phenyl-3-coumaranylchrysanthemate.
 9. A compound according to claim 2 which is5-benzyl-3-coumaranyl chrysanthemate.
 10. A compound according to claim1 wherein R is a cyclopropane moiety of the formula: ##SPC8##
 11. Acompound according to claim 10 which is 3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate.
 12. A compound according toclaim 10 which is 5-chloro-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate.
 13. A compound according toclaim 10 which is 5-nitro-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate.
 14. A compound according toclaim 10 which is 5-methoxy-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate.
 15. A compound according toclaim 10 which is 5-methyl-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate.
 16. A compound according toclaim 10 which is 5-phenyl-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate.
 17. A compound according toclaim 10 which is 5-benzyl-3-coumaranyl2,2,3,3-tetramethylcyclopropanecarboxylate.